I N THE NAME OF GOD F RACTURES OF THE KNEE By: Foroogh Jafari

Fractures of the knee include fractures of the patella, femoral condyles, tibial eminence, tibial tuberosity, and tibial plateau. Direct and indirect forces can cause these fractures.

E PIDEMIOLOGY : Frequency: United States Patellar and tibial plateau fractures each account for 1% of all skeletal fractures. Distal femoral condyle fractures account for 4% of all femur fractures.

M ORTALITY /M ORBIDITY : Fractures of the knee can result in neurovascular compromise or compartment syndrome, with resultant risk of limb loss. Soft-tissue infection or osteomyelitis can occur with open fractures. Other complications include: nonunion, delayed union, osteoarthritis, avascular necrosis, fat embolism, and thrombophlebitis.

H ISTORY : Direct or indirect trauma with resultant pain and edema. Patella fracture:Caused by a direct blow, such as a dashboard injury in a motor vehicle accident or a fall on a flexed knee, also caused by forceful quadriceps contraction while the knee is in the semiflexed position (eg, in a stumble or fall).

Femoral condyle fractures: due to axial loading with valgus or varus stress.

Tibial eminence fracture: Due to a direct blow to the proximal tibia with the knee flexed such as falling off a bicycle, also due to hyperextension with varus or valgus stress, such as in motor vehicle collisions or athletic accidents (Tibial eminence avulsion fractures occur most often in children aged 8-14 years but can also occur in the skeletally mature patient)

Tibial tubercule fracture:Usually occur with jumping activities such as basketball, diving, gymnastics, and football, more common in males than in females, more common in adolescents; infrequent in adults.

Tibial plateau fracture:Caused by axial loading with valgus or varus forces, such as in a fall from a height or collision with the bumper of a car, due to the impaction of the femoral condyle into the tibial plateau. In elderly persons and those with osteoporosis, tibial plateau fracture can occur with minor trauma. Patient is generally unable to bear weight. The lateral tibial plateau is fractured more frequently than the medial plateau.

P HYSICAL EXAM When examining a patient for a knee fracture, one should first examine the patient for edema, ecchymosis, and point tenderness. A careful neurovascular examination should be performed. Ask the patient to perform a straight-leg raise against gravity to check the integrity of the extensor mechanism, which commonly is disrupted with transverse patellar fractures caused by indirect forces.

P ATELLA FRACTURES Patients present with pain directly over the patella. The patient may have pain with leg extension or be unable to extend the knee with a severe fracture.

F EMORAL CONDYLE FRACTURES Patient will present with pain over the distal femur and often will have a hemarthrosis. Patients are often unable to bear weight.

T IBIAL EMINENCE FRACTURES Patients may present with a knee effusion and pain. Patients may represent with an avulsion of the tibial attachment of the anterior cruciate ligament.

T IBIAL TUBERCLE FRACTURES Patients present with pain over the anterior tibia about 3 cm distal to the articular surface. In severe fractures, the patient may be unable to extend the knee.

T IBIAL PLATEAU FRACTURES Often, patients present with a knee effusion, and tenderness will be present over the medial or lateral plateau. Up to 30% of tibial plateau fractures are associated with knee ligamentous injuries (medial collateral or anterior cruciate ligaments with lateral plateau fractures, lateral collateral or posterior cruciate ligaments with medial plateau fractures).

C AUSES Knee fractures may be caused by the following: Trauma (direct or indirect) Chronic stress Pathologic conditions

IMAGING S TUDIES Radiographs Obtain anteroposterior, lateral, and oblique radiographs of the knee.Four views have been shown to be superior to two views in detecting fractures. Oblique views are particularly useful in detecting subtle tibial plateau fractures (internal oblique profiles lateral plateau, external oblique profiles medial plateau). Oblique views also better identify obliquely oriented femoral condyle fractures.

An axial (or sunrise) view of the patella is useful for detecting vertical patellar fractures, which frequently are missed and nondisplaced. Transverse fractures are most common, followed by comminuted and avulsion-fractures. Adding a sunrise view increases the negative predictive value of radiographs for ruling out patellar fracture. A fat-fluid level (lipohemarthrosis) may be identified on a lateral view of the knee; this finding indicates an intra-articular fracture.

Radiographic evidence of ligamentous injury may be present: An avulsion fracture at the site of attachment of the lateral capsular ligament on the lateral tibial condyle (Segond fracture) is a marker for anterior cruciate ligament rupture. Cortical avulsion fracture of medial tibial plateau (uncommon) is associated with tears of the posterior cruciate ligament and medial meniscus.

CT SCANS AND MRI S CT scans may be necessary to fully delineate the extent of tibial plateau fractures and other complex knee fractures. Compared to CT scans, plain radiography underestimates the amount of articular depression of tibial plateau fractures in most tibial regions. This is significant as the amount of tibial plateau depression is an indicator for operative repair.

CT scans are also useful in severely injured patients when obtaining radiographs in all angles is difficult. MRIs also are useful and have the added benefit of depicting associated soft-tissue (eg, ligamentous, meniscal) injury.

P ROCEDURES Arthrocentesis may be of diagnostic and therapeutic benefit for tense effusions. Presence of blood and glistening fat globules indicates lipohemarthrosis, which is pathognomonic for intraarticular knee fracture.

P REHOSPITAL C ARE Document the neurovascular status. Apply a sterile dressing to open wounds. Splint the injury. Administer parenteral analgesics for isolated extremity injury.

C ARE FOR VARIOUS FRACTURES IS AS FOLLOWS : Patellar fracture Nondisplaced transverse fractures with an intact extensor mechanism are treated with a knee immobilizer, crutches, restriction to only partial weight bearing, and 6 weeks of immobilization. Displaced fractures, or fractures associated with a disrupted extensor mechanism, are referred to orthopedics for possible open reduction and internal fixation. A partial or total patellectomy may be required for severe comminution. Patients with open fractures should receive antibiotics and orthopedics should be consulted for emergency irrigation and debridement.

Femoral condyle fracture These may be supracondylar, intercondylar, or condylar. Due to the proximity of the neurovascular structures, a thorough neurovascular examination must be obtained. Obtain an orthopedic consult. Nonoperative management may be used for nondisplaced or incomplete fractures. Open fractures, displaced fractures, and those with neurovascular injury will need operative fixation

Tibial spine fracture For a nondisplaced fracture (and stable knee joint), immobilize the knee. Obtain an orthopedic consultation for an unstable knee, a complete avulsion of the tibial spine, or a displaced fracture for possible surgical fixation.

Tibial tubercle fracture For nondisplaced fractures, immobilize the knee. Obtain an orthopedic consultation for displaced fracture to consider open reduction and internal fixation.

Tibial plateau fracture Immobilize nondisplaced fractures and have patient remain nonweightbearing. Obtain an orthopedic consultation for displaced (depressed) fractures, which require open reduction and internal fixation.Articular depression of greater than 3 mm may be considered for surgery.

The goal of treatment is a stable, aligned, mobile, and painless knee joint to minimize risk of posttraumatic osteoarthritis